期刊

Nanoscale Horizons

标题

High-temperature driven inter-valley carrier transfer and significant fluorescence enhancement in multilayer WS2

作者

Heyu Chen, Yuanzheng Li, Weizhen Liu, Haiyang Xu, Guochun Yang, Jia Shi, Qiushi Feng, Tong Yu, Xinfeng Liu and Yichun Liua  

摘要

It is quite necessary to understand and control the essential carrier dynamic behaviors of two-dimensional WS2, which is regarded as a very promising material for integrated nanoelectronic and optoelectronic devices. Herein, a high-temperature driven carrier transfer process of multilayer WS2 nanoflakes is proposed. The established model, involving the inter-valley transfer process of photocarriers from the Λ/Γ point to the K point, predicts the significant emission enhancement of the K → K direct transition at high temperatures, which is verified by both theoretical calculations and experimental observations. On the one hand, variations in the estimated population ratio of photo-carriers with increasing temperature well support the proposed model. On the other hand, temperature-dependent photoluminescence spectra clearly show that the K → K direct emission intensity is remarkably enhanced by ∼300-fold as the temperature is elevated to 760 K. Time-resolved fluorescence spectral studies confirm the occurrence of the inter-valley carrier transfer process in the multilayer WS2. These results provide solid evidence for the proposed inter-valley carrier transfer model. Such a mechanism could not only be applied to improve the luminescence intensity of indirect-band-gap semiconductors, but also be further extended to design optoelectronic devices which have special requirements on controlling the carrier dynamic behavior.

原文链接

https://pubs.rsc.org/en/content/articlelanding/2018/nh/c8nh00123e